1. Field of the Invention
The present invention relates to a magnetic head used for a magnetic recording apparatus such as a video cassette recorder, a digital audio tape recorder, a floppy disk drive or a hard disk drive for recording and reproducing information at a high density for a magnetic recording medium.
2. Description of the Prior Art
Previously, a magnetic head made from a ferrite is used for a magnetic recording apparatus such as a video cassette recorder. However, in order to record and reproduce information at a higher density, it is needed to increase the coercive force (hereinafter referred to as H.sub.c) of a recording medium, and a metal tape of H.sub.c of 80 kA/m or higher is used to increase coercive force. In order to avoid magnetic saturation, a magnetic head is developed to have a part of a magnetic core made of a metallic soft magnetic material such as a Sendust alloy, a cobalt based super-structured alloy or an iron-based nitride alloy having a high saturation magnetic flux density (hereinafter referred to as B.sub.s) and a high magnetic permeability.
In a prior art metal-in-gap (MIG) head (U.S. Pat. No. 5,001,590), a pair of metallic magnetic films of high B.sub.s are formed on opposing planes of magnetic cores made of ferrite to form a gap between them. Then, SiO.sub.2 layers and barrier layers are formed successively to cover each of the metallic magnetic films as a main-gap layer. Then, the gap is adhered by fusing an adhesive glass between the opposing barrier layers abutted on each other. (As disclosed in Japanese Patent laid open Publication No. 276410/1989, a chromium layer as the barrier layer is preferable for suppressing the reaction between the metallic magnetic films and SiO.sub.2.) When a magnetic tape slides on such a magnetic head having SiO.sub.2 as a main gap material, the metallic magnetic films are abrased selectively on sliding planes and a space is generated eventually between the magnetic tape and the magnetic gap. Then, the output signals of the magnetic head decreases due to a spacing loss caused by the selective abrasing.